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本文从细观力学出发,提出一种新的基于物理失效机制的细观失效准则。该准则基于Mohr-Coulomb准则并侧重考虑了压缩载荷下组分材料的损伤模式和失效机制,指出压缩失效时压应力会阻碍断裂面的剪切破坏,并深入研究了纤维压缩失效模式,在纤维折断失效准则中引入纤维折断破坏面上剪切强度的概念。采用本文提出的准则对WWFEII(the Second World Wide Failure Exercise)中单向板算例进行失效预测和定量评估,并与Puck、Pinho、Cuntze、Carrere、Tsai-Ha、Hansen和Huang准则的预测结果进行对比,表明在三向载荷下本文提出的细观失效准则在8种失效准则中拟排名第一。研究了静水压力对基体强度的影响,得出影响因子仅与单轴压缩断裂角有关的结论。探讨了WWFEII各强度准则间关于失效包线是“张开”还是“封闭”的重要分歧,认为复合材料在三向压应力状态下失效包线是否为“张开”和“封闭”没有统一的标准答案,而是与复合材料的纤维体积含量、纤维和基体的力学性能、基体随静水压力力学性能的变化及基体的单轴压缩断裂角有关。
In this paper, based on meso-mechanics, a new criterion of microseismic failure based on physical failure mechanism is proposed. The criterion is based on the Mohr-Coulomb criterion and focuses on the damage modes and failure mechanisms of component materials under compressive loads. It is pointed out that compressive stress will hinder the shear failure of the fracture surface under compressive failure and further study the failure modes of fiber compression. Fracture Failure Criteria Introduced the concept of fiber shear failure on the shear strength of the surface. The failure criterion and the quantitative evaluation of the one-way plate in the WWFEII (the Second World Wide Failure Exercise) are evaluated and compared with the prediction results of the Puck, Pinho, Cuntze, Carrere, Tsai-Ha, Hansen and Huang criteria The comparison shows that the mesoscopic failure criterion proposed in this paper is the first of eight failure criteria under the three-direction load. The effect of hydrostatic pressure on the strength of the matrix was studied. The conclusion that the influence factor is only related to the uniaxial compression fracture angle was obtained. The main differences between the WWFEII strength criteria on failure envelope is “open” or “closed” are discussed. It is considered that the failure of the composite under the three-direction compressive stress is “open” and There is no uniform standard answer for “closed”. Instead, it is related to the fiber volume content of the composite, the mechanical properties of the fiber and the matrix, the change of the matrix with hydrostatic mechanical properties, and the uniaxial compressive fracture angle of the matrix.